Torque measuring wrench



Jan. 24, 1939. H. w. ZIMMERMAN 2,144,731

roRQun usAsun1NG warmen Filed Jan. 2s, 1937 2 sheets-sheet 1 Jan. 24, 1939. H. w. ZIMMERMAN 2,144,731

TORQUE MEASURING WRENCH Filed Jan. 28, 1937 2 Sheets-Sheet 2 Jdorrgf Patented Jan. 24,- 1939 PATENT OFFICE 'ronQUE MEASURING yWRENCH Herman W. Zimmerman, North Chicago, IIL, as-

signor, by mesne assignments, to Frederick G. Wacker and vGrace J. Wacker, Lake Forest, Ill.

Application January 28, 1937, Serial No. 122,839

20 Claims.`

My invention relates to wrenches and it has to do more particularly with wrenches of the class disclosed in United States Letters Patent No.4

i' 2,007,880, granted to John H. Sharp, on July '5 9, 1935, andwhich are adaptedfor measurement of the force ortorque applied through the wrench in tightening or loosening bolts, studs, nuts, and the like.

One of the objects of my invention is to provide l an improved wrench of the foregoing character, e and which is of simple and sturdy construction, 'is inexpensive to manufacture, is so constructed thatthe parts thereof may be readily andeasily assembled and disassembled, and which is adapted for the performance of its torque measuring function in a uniform and highly eflicient manner.

Another object is to provide an inexpensive torque measuring wrench well suited for 'tightening and loosening various bolts, studs, nuts, etc., used in connectionl with automotive and other engines, such, for example, as the cylinder head studs thereof, all of which should be tightened to the same extent to place them under a uniform tension to insure proper engine performance. y

A further object is to provide a torque measuring wrench having spring members through which the force employed in tightening and loosening the bolts. nuts, etc., `is applied, the arrangement being such that the spring members are mounted in opposed relation independently of each other so that one spring member does not in any way aect the yieldabl'e function of the other, and either of the spring members may be adjusted member, whereby the spring members may be set `to perform accurately under all load conditions.

Still another object is to provide a wrench of the foregoing character in which the spring memment with a bolt, nut, stud, or the like, the arrangement being such that the rockable member is held normally in a neutral position independently of the pressure of either of the spring members and, as therockable member` is rocked in" either direction, only one of the spring members is active at a time.

` Additional objects are to provide a tensionI on the foregoing character having a self-conwithout affecting the tension of the other spring' bers are arranged between a wrench handle and f' a rockablemember having provision for engagetained and detachable indicating unitincluding adjustable indicating means so located as to facilitate observation thereof by the mechanic as well as to facilitate handling of the wrench; and to vprovide a wrench of the foregoing kind in which the rockable member and the spring members may be separately and independently assembled and disassembled without disturbing the position or condition of each other.

Other objects and advantages will become apparent as this description progresses, and by reference to the drawings, wherein.-

Figure l is a top plan view of-one form of wrench structure embodying my invention;

Fig. 2 is a side elevational view of the forward portion of the Wrench structure shown in Fig. 1; Fig. 3 is a horizontal sectional view taken throiigh-the upper or indicator portion of the wrench, the same being taken substantially on line 3-3 of Fig. 4;

Fig. 4 is an enlarged vertical sectional view of the structur shown in Figs. 1 and 2;

Fig. 5 is` a horizontal section taken substantially on line 5 5 of Fig. 4;

Fig. 6 is a section taken substantially on line 6-6 of Fig. 4; and 4 Fig. 7 is a section taken substantially on line 'I-I of Fig. 4..

'I'he wrench shown in the drawings includes a head part I0 having an elongated handle II (Fig. l) extending rearwardly therefrom. The forward end of the handle- II is received within an opening I2 in the head I0 and it issecured therein in any suitable manner, as by the pin I3.

The' forward end or nose of the head I0 takes the form of spaced upper and lower shelf-like and parallel portions Il, I5 (Figs. 2 and 4) providing a rock space III in which is received a part-circular, rockable member I6 which is adapted for operative connection with the work. The member I6 is rockably supported in place in the 4following manner: 'I'he shelves I4 and I5 are provided with aligned screw-threaded openings I1, I8, in which are received threaded rings or busnings I9 and 20, respectively. The upper and lower surfaces of the rock member I6 are provided with aligned grooves 2| in which annular tongues 22 on the inner ends of the bushings I9, 20 are received, the tongues 22 fitting into the grooves 2| in such a way that the member I6 is permitted to take a free rotary rock movement without any material lateral or radial play or looseness. 'I'he o uter ends of the bushings I9, 20 are provided with lateral anges -23 which, when the bushings are screwed home within the shelves I4, I5, seat firmly on the outer surfaces of these shelves, the flanges 23 serving as stops preventing the bushings I9, 20 from being screwed in so far as to tend to lock or cramp the rockable member I6. The bushing tongues 22 are of slightly less thickness than the threaded portion of the bushings, providing bushing shoulders 24 against which the upper and lower` sides of the rockable member I6 seat when the bushings are screwed home, thereby preventing vertical play or looseness of the member I6 without hindering its free rockable action. With this arrangement, it will be seen that the member I5 is confined between the shelf-like portions I4, I5 for rock movement only. The bushings are locked in assembled position by screws 23a carried by the wrench head I0, the arrangement being such that the heads of such screws seat in suitable recesses formed in the peripheral edges of the bushing flanges 23.

The rockable member I6 is directly connected to the nut, bolt, stud or the like by detachable work engaging means which includes a rectangu-l larly-shaped elongated adapter member 25 (Figs. 4 and 5) which is received in a similarly shaped and sized opening 26 provided in the member I6 at the rock center thereof. To detachably secure the adapter 25 in place, the member I6 is provided with a radially-disposed opening 2B leading from the outer rounded edge of such member into its opening 26, and the inner portion oi this opening 28 is screw-threaded; for reception of a set screw 21 which, when screwed into place, engages the adapter member 25 and locks the same in the desired position with respect to the member I6. The outer portion of the opening 28 (Fig. 5) is unthreaded and it is constructed and arranged to permit the free entry of the locking screw 21 to the threaded portion receiving. the same. The outer end of the adapter 25 (Fig. 4) projects downwardly through and beyond the lower bushing 20 and is constructed to receive a socket 29 of selected size or other suitable coupling member (not shown) which is adapted to directly engage the bolt, stud, or the like.

In order to insure a free and smooth rock movement of the member I6 at all times. it may be desired to lubricate the bearing surface between such member and the bushings I9, 20. To that end, ports or openings 32 (Fig. 4) are provided in member I6 connecting the opening 26 with the grooves 2i. Oil, or any other suitable lubricant, inserted in the opening 26 will readily find its way through the ports 32 into the grooves 2i and lubricate the bearing surfaces between the member I6 and the bushings I3, 20.

Rock movement of the member I6 in both directions is opposed by spring means, the extent of movement of the member I6 and the deflection of the spring means being measured to indicate the amount of torque or force applied through the wrench in tightening Yor loosening the stud, etc. This spring means will now be described. I'he wrench head I0, on the opposite sides of the handle I I, is provided with similar spring chambers 33, 34 (Fig. 5) which extend substantially parallel with the handle II on the opposite nsides of the rock center of the member I5. Coil springs 35 and 36, preferably of identical kind, are

mounted in the spring chambers 33,' 34 and they A is connected at its forward end to the space I0* between the shelf-like portions I4, Il by reduced openings 39,v 40, in which the stems of T-headed plungers 4I and 42 are slidabiy received. The heads 4In and 42 of these plungers are slidably received within the spring chambers 33, 34 and are constantly urged forwardly so that the T heads 4I"l and 42* ynormally seat against the forward end wall of the spring chambers, the springs 35 and 36 being confined under the desired tension between the T-heads of the plungers and the screw plugs 31. f

The stems of the plungers 4I and 42 are of such length that when they are fully extended they project into the space III between the shelf-like portions I4 and I 5 far enough to engage arm-like portions I6, I6b formed at the opposite sides of the rockable member I6. The arm-like portions I6, I6b (Fig. 5) of the rock member I6 are substantially identical and they constitute the end parts of the part-circular portion of such member. The portions of these arms I6* and I6 which engage the plungers'4i and 42 are rounded to facilitate the rocking movement of the arms against the plungers and to minimize friction and wear therebetween. With this arrangement, the springs 35, 36 normally hold the plungers 4I and 42 fully extended with their head portions firmly seated against the forward ends o! the spring chambers, and the plunger stems, due to the length thereof, merely contact the arms I6* and I6b of the rock member I6, holding the latter in a neu-'trai position without exerting spring pressure on either arm in either direction. In other words the plungers 4I, 42 normally act merely as stops holding the member I6 in a neutral or atrest position; and under conditions of use they serve as the means for operatively connecting the member I6 and the springs 35, 36. It will, therefore, be'seen that either spring 35 or 36 may be adjusted independently of the other spring without affecting the position of the rock member I3 or without affecting the relation between the other spring and the rock member The T-headed plungers insure this independent relationship. It will also be seen that when the wrench is applied to a bolt or nut and is moved in a clockwise direction, to tighten the same, resistance to this movement onered by the nut or bolt will be indicated by the extent of relative counterclockwise movements between the rock member'i6 and the handle II as permitted by deflection oi' the spring 36. In other words, as soon as the resistance offered by the nut or bolt exceeds the resistance offered by the spring 36, continued movement of the handle II will result in compression of the spring 36 and the relative movement of the member I6, which compression and movement may be measured to determine the force or torque applied through the handle necessary to overcome the resistance oifered by the nut or bolt. In the case of loosening the bolt, the handle I.I is moved in opposite or counterclockwise direction, at which time the spring 35 becomes effective in the accomplishment of the same relative action as described in connection with the tightening of the bolt. The structure so far described is so arranged that each spring 35 or functions independently of the other so that variation in the tension of either spring will not aiect the force resisting function of the other spring.

In order that the operator may determine the amount of force or torque required to tighten or loosen any particular bolt or nut, I provide a self-contained indicating unit conveniently and detachably located on the wrench head I0. Specically, this indicating unit includes a casing 5I) (Fig. 4) mounted upon the top of the wrench head and secured thereto by screws 5| passing therethrough and engaging suitable threaded openings in the upper Wall of the wrench head. The rear under side of the casing is provided with a pin 52which engages a suitably provided opening 53 in the upper rear wall of the wrench head, which serves to properly position and align the casing 50 with the wrench head for a purpose which will become obvious hereinafter.

The casing' 59- Fig. 4) supports indicator mechanism which includes a dial 54 with suitable graduations indicating, preferably, inch-pounds pressure. This dial is covered by a suitable, transparent cover 55 which may be formed of any suitable material. The dial 54 and cover 55eme located at the rear of the wrench head adjacent the handle i I where it may be more conveniently observed by the operator and where it is out of the way, so to speak, so that the operator may more readily grasp the wrench head for manipulating the wrench as a whole.

The indicator mechanismiurther includes a pointer 56 mounted above the dial 54 and carried by a member 51 projecting upwardly through the cover 54 and having an accessible knob portion 58. Thefmember 5T is provided at its lower end with a slightly tapered opening 59 in which the complementally shaped upper end of a shaft 6I) is frictionally tted. The t between the shaft 66 and the opening 59 is such that the member 51 and shaft 60 normally rotate together but, upon applying 'sufficient pressure rotatably to the knob 58 with the shaft 60 held stationary, the member 51 may be rotated relative to the shaft 60 to position the pointer 56 at any particular point with respect to the diaL-for example, the. zero point thereon.

The lower end of shaft 60 finds a bearing in an opening 6| (Figs. 4 and '1) in the lower patof the indicator casing, and this shaft iixedly supports a relatively small pinion 62 which is engaged with a. longitudinally located rack 63. This rack and the pinion 62 are confined in engagement with each other by a bracket member 64 having legs 64 of a length substantially equal to the thickness of the pinion 62 and rack 63 and spaced apart a distance only slightly greater than the combined width of the rack and pinion. 'Ihe bracket 6l is secured in place by screws 65 (Fig. 7) passing through the bracket legs 64* and engaging suitably threaded openings in the bottom wall of the casing 56.

The indicator mechanism so far described is connected to the rockable member I6 through the rack 63 which extends forwardly from the pinion 62 where it engagesanother and largerv pinion 66 fixed to a shaft 61. The upper end 68 of the shaft 61 is reduced and-is rotatably supported in an opening 69 in the' upper forward wallof the indicator casing. The pinion 66 and shaft Glare normally supported in position, and

the pinion 66 and rack63 are normally held in engaging position, by a bracket 10 similar to the bracket 6l. The legs 10* of the bracket 10 are spaced apart suiiiciently to accommodate the larger size pinion andl the rack therebetween, y and they are of a length substantially equal to the thickness of the gear 66 and rack so that these parts are conilned normally as shown in Figs. 4 and 6. The bracket 10 is secured in position by screws passing through the legs 10* thereof and engaging suitably threaded openings in the adjacent upper wall of the indicator casing.- To further insure `smooth operation of the rack and pinion structure, the rack 63 is yieldably pressed into engagement with the pinions 62and 66 by a spring 638L having one end secured at 63b to the casing 50 and its other end attached to the rack 6l.

The lower end of the shaft 61 supports a clutch-like member II having a hub'portion secured thereto by a pin 12. The clutch-like member 1| is provided with a lateral, annular flange 1I, in which are mounted, diametrically opposed, depending pins 13 which` are received'in aligned openings 14 in the upper face of the rockable member I6.

It will be seen, from the foregoing, that upon tightening a bolt, stud or the like with this wrench, deflection of the spring 36 and resultant relative counter-clockwise movement of the rock member I6 will result in counterclockwise movement of the clutch-like member 1 I, the pinion 66, and like movement of the pointer 56 through lthe resulting movement of the rack 63 and pinion 62. Rock movement of themember I6 in an opposite direction, as when loosening a bolt, stud or the like, will result in the opposite movement of these parts and clockwise movement of the pointer 56. The relative sizes of the pinions 66 and 62 provide for a substantial movement of the pointer 56 upon a slight movement of the rock member. The springs 35 and 36 are so constructed that a predetermined inch-pound pressure is required to deect them to a predetermined extent, which deection is indicated by the movement of the member I6. This deflection, although of slight extent, is readily registered in terms of inch-'pounds through the rack and pinion structure described.

4It will be clear from the foregoing that the purpose of my invention'will be best served by rst applying the -wrench to the nut, stud or the like, then setting the pointer 56 to the zero (or some other) mark on dial 5I, and, if the bolt is being tightened, theoperator may determine through the extent of movement of the pointer 56 the amount of inch-pounds pressure or torque required to set up the stud or bolt to any desired errtent. In this way, the operator may avoid breakage ofthe nut or bolt by avoiding the use of excessive pressure, as may happen in case the pressure applied exceeds the tensile strength of the material of the stud or bolt. Also, the operator, in consecutively tightening a series of studs or bolts, as, for examp1e,.'the cylinder head studs of an automotive engine, may initially set the -wrench pointerl to zero when applying -pressure to each stud and then set up l each stud to the same predetermined extent. The

same procedure may be employed, if the wrench is used for loosening studs, bolts. or the like.

For example, if the desired or predetermined pressure has been exceeded in setting up the stud or bolt, the wrench may be actuated, without removing it from the stud to loosen thev same to that point on' the dialindicating the inchpounds pressure required -to further move such stud or bolt.

Itis believed that the objects and advantages l sturdy, and it wm serve its intended purpose indefinitely without repair and adJustment. It

is accurate in its indicating function. Accuracy at all times and under all weather conditions is insured. The parts may be readily and easily assembled and disassembled, as, for example, the rock member i8 may be readily assembled or disassembled without affecting the springs acting thereon, since the T-head plungers prevent the springs from affecting the normal at-rest position of the rock member when the handle is at rest without pressure being exerted thereon.

It will. be understood that, although I have shown only one form of structure embodying my invention, changes in details and arrangements of parts may be resorted to without departing from the spirit and scope of my invention as defined by the claims that follow.

I claim:

1. In a device of the class described, a wrench head, a handle extending from one end `of said head, a member having opposed arm-like elements thereon mounted for rock movement at the other end of said head, coil spring members carried by said head and having their axes extending longitudinaliy of said handle in alignment with said arm-like elements, plunger members slidably carried by said head between said spring members and arm-like elements, means for limiting movement of said plungers forwardly under the influence of said springs to a predetermined point whereat said plungers merely abut said arm-like elements without exerting pressure on the latter, whereby said rock member in the inactive condition of the wrench is held in a predetermined balanced condition, work engaging means carriedy by said rock member on the rock center of the latter, and indicating means connected with said rock member registering the relative rock movement between the latter and said head and extent of compression of said spring members.

2. In a device of the class described. a wrench head having a pair of spaced, longitudinally extending and substantially parallel spring chambers formed therein and also having reduced slideways extending forwardly from said spring chambers, a handle on the rear end of said head, a rockable member mounted in .the front end of said head and having a pair of opposed arm-like elements disposed in alignment with said slideways, springs mounted in said chambers in such a way as to be flexed axially of the latter, plunger members having a stem portion mounted in said slideways and another portion mounted in said spring. chambers, said plungers being provided with shoulders adapted to engage said head at the end of said spring chambers adjacent said arm-like elements for limiting the extent to which said plunger members may be urged forwardly by said springs, said plunger stem portions being of sufficient length forwardly of said shoulders that when said shoulders engage said head said stem portions abut said arm-like elements without exerting pressure thereon, means carried by and located on the rock centerof said rockable4 member and having provision for engaging said rock member with the work, and indicator means associated with said rockable member for registering the extent of relative rock movement between said head and rock member.

3. In structure of the class described, a wrench head having a rock space formed in its forward end, spaced, parallel and longitudinally extending spring chambers, and reduced slideways leading from said spring chambers to said space, a rock member mounted in said space and having movement of the latter.

opposed arm-like elements aligned with said slideways. plungers having stem portions slidably mounted in said slideways and enlarged head portions slidably mounted in said spring chambers, springs mounted in said chambers and engaging said plunger heads to normally urge said plungers forwardly with their heads seated against the forward ends of said spring chambers, said plunger stern portions being of such length when said plungers are urged fully forward that they merely abut said arm-like elements without exerting active pressure there against providing a balanced support for said rock member when the wrench is inactive so that movement of said rock member in either direction will merely compress the respective of said springs without affecting or being affected by the tension or position of the other spring, work adapter means mounted on the rock center of said rock member, and indicating means connected to said rock member for registering relal tive movement between said head and rock member,

4. In structure of the class described, a wrench head, a handle on one end of said head, a rock member on the other end of said head and having opposed arm-like elements thereon, spring members carried by said head in' alignment with said arm-like elements, plunger members slidably carried by said head in alignment with said arm-like elements and normally serving as stops limiting said rock member to a neutral or non-pressure position. said plungers being operatively connected with said spring members whereby one of the latter is depressed by rocking said rock member in either direction without affecting or being affected by the other spring member, work engaging means connected to said rock member in axial alignment with the rock center thereof, and indicating vmeans connected to said rock member and registering the extent of relative rock movement between the latter and said head and the extent of compression of the respective active spring member.

5. In structure of the class described, a wrench head having forwardly extending, spaced shelflike portions having aligned threaded openings therein, a readily detachable rock member mounted between said shelf-like portions, said member having aligned annular grooves in its opposite faces, threaded bushings mounted in said threaded openings and having tongues seated in the grooves of said rock member, work engaging means detachably carried by said rock member, means yieldably opposing movement of f.

said rock member, and indicating means connected to said rock member and registering rock `6. In structure of the class described, a wrench head having its forward end shaped to provide a rock space with the opposed side walls thereof having threaded openings therein, a rock member mounted in said space and having aligned annular grooves in its opposite faces, means for mounting said rock member in said space including a pair of rink-like threaded bushing members mounted in said threaded openings and having extensions projecting into said rock memfber grooves, means for locking said bushings in assembled, position, work engaging means detachably carried by said rock member, said rock member being readily removable by detaching said bushings and said work engaging means, and means by which a lubricant may be supplied through said rock member to the grooves therein either direction, and means for indicating the extent of movement of said .rock member comprising a self-contained detachable unit including a casing, means for securing said casing to said head, 'a dial, a pointer, a clutch member detachably engaged with said rock member, and rack and pinion means between said clutch member and pointer transmitting motion of said rock Y a self-contained detachable unit including an' elongated casing mounted upon and extending substantially throughout the length of said head,

means detachably securing said casing to saidl head, a .dial mounted in said casing adjacent said handle, a pointer rotatably movable with respect to said dial, a rotatable clutch member carried by said casing and `projecting downwardly ltherefrom and operatively engaged with said rocii member, and means for transmitting rotation of said clutch member to lsaid pointer.

9. In structure of the class described, a wrench head, a handle on one end thereof, a rock member e on the other'end thereof, spring means opposing rock movement of said member. in either direction,l and'means for indicating the extent of movement of said rock member comprising a self-contained detachable `unit including a casing, means detachably securing said casing to said head, a dial in said casing, a pointer rotatable with respect to said dial, a support for said pointer, a clutch-like member positively connected to said rock member, connections between said clutch member and said pointer support for rotation of the latter as said rock member rocks, including a slip connection permitting said pointer support and pointer to be rotated independently of movement of said rock member whereby said pointer may be independently set to any predetermined position relative to said dial.

10. A torque measuring wrench comprising a head member, a `handle on one end thereof, a rock member on the other end of said head member, spring' means opposing rock movement of said rock member in either direction, and means for indicating the ext/ent of movement of said rock member as opposed by said spring means to indicate the amount of force or torque applied through the wrenc including a self-contained unit comprising a cw ing mounted on said head,

a dial, a pointer movable with respect to the dial, a clutch member operatively associated with said rock` member, and means between said clutch member and pointer for transmitting motion of said rock member to said pointer.

l1. A torque measuring wrench comprising a head "member, a, handle onl one endthereof, -a rock member on the other end of Vsaid head member, spring means opposing rock movement of said rock'membe'r in either direction, a'nd means for indicating the extent of movement of said 'rock member comprising a unit including van elongated casingportion extending substantially throughout the length of said head, a dial mounted in said casing, at -the end of said head member adjacent said handle. a pointer rotatably movable relative to said dial, a rotatable clutch member carried by said casing and pro- `iecting toward and into operative engagement with said rock member for movement therewith, and means for transmitting movement of said clutch member to said pointer.

12. A torque measuring wrench comprising a head member, a handle at one end thereof. a rock member at the other end of said head member, spring means opposing rock movement of for indicating the extent of movement of said rock member comprising a unit including a casing, adial in said casing, a pointer rotatable with respect to said dial, a support to which said pointer is xedly secured, a clutch member positively connected. to said rock member, connections between said clutch member and said pointer support for rotation of the latter as said rock member rocks, said connections including a rack and a slip connection between said rack and said pointer support, permitting the latter to be rotated independently of movement of said rock member when the latter is held stationary whereby said pointer may be independently set to any predetermined position relative to said dial. e

i3. A torque measuring wrench comprising a head member, handle means on one end thereof, a rock member pivotally supported at the other end of said head member and having an arm-like element thereoma spring member carried by said head member in alignment with saiduarm-like element and yieldable in a direction substantially' longitudinally of said handle means, a plunger member slidably carried by said head member inaiignment with said arm-like element and provided with means positively limiting Islide movement thereof toward said arm-like element, said lplunger 'member being engaged by said spring member and constantly urged forwardly toward vsaid arm-like element, work engaging means inber, a'rock member mounted for rock movement at the forward end of said head and having an arm-like element disposed in substantially axial alignment with said slideway, a spring member mounted in said ychamber and adapted to hex in a direction axially' of said slldeway, a plunger member having a stem portionV mounted in lsaid 'slideway and a head portion mounted in said spring chamber, said plunger head limitig the extent of movement of-'said plunger forwardly through said slideway under the influence of said spring member, said plunger stem being of such ieigth that in its fully extended'pomtion it shuts 70 said arm-like element without exerting prsure thereon, work engaging means including a work adapter carried-by-said` rock member -onthe rock center thereof, and lindicating means operatively connected withsaid rockable member for registering the extent of relative rock movement between said rock member and head.

15. In structure of the class described, a Wrench head provided with forwardly extending, spaced shelf-like portions having aligned openings therein, a detachable rock member mounted between said shelf-like portions, said member having aligned annular grooves in its opposite faces, guide members mounted in said openings and having inwardly extending tongues engaged in the grooves of said rock member for rotative support and guidance of the latter, means for detachably securing said guide members in said openings, work engaging means detachably carried by said rock member, means yieldably opposing movement of said rock member, and indicating means associated with said rock member for registering the extent of rock movement of the latter.

16. In structure of the class described, a wrench head having its forward end shaped to provide a rock space with the opposed side walls thereof having openings therein, a rock member mounted in said space and having aligned annular grooves in its opposite faces, means for mounting said rock member in said space including a pair of ring-like members mounted in said openings and having extensions projecting into said rock member grooves, means for securing said ring-like members in assembled psition, work engaging means detachably carried by said rock member, said rock member being readily removable by detaching said ring-like members and said work engaging means, and means by which a lubricant may be applied through said rock member to the grooves therein without detachment of any parts.

17. In structure of the class described, a wrench head, a rock member carried thereby, spring means opposing rock movement of said member, and means for indicating the extent of movement of said rock member comprising a self-contained detachable unit including a casing, means for securing said casing to said head, rotatable indicating structure, a clutch member detachably engaged with said rock member, and rack and pinion means between said clutch member and rotatable indicating structure for transmitting motion of said rock member to said structure.

18. A torque measuring wrench comprising a head member, a rock member carried thereby, spring means opposing rock movement of said rock member, and means for indicating the extent of movement of said rock member as opposed by said spring means to indicate the amount of force or torque applied through the Wrench including a self-contained unit comprising a casing mounted on said head, a movable indicator supported by said casing, a clutch member operatively associated with said rock member, and means between said clutch member and indicator for transmitting motion of said rock member to said indicator.

19. In structure of the class described having a wrench head, a rock member carried by said head and spring means opposing relative rock movement between said head and rock member; means for indicating the extent of movement of said rock member in terms of pressure applied comprising a self-contained detachable unit including a support member, means for detachably securing said siipport member in a predetermined position upon said head, rotatable movement registering means carried by said support member, clutch means operably engaged with and movable with said rock member, said rock member and clutch means being so constructed and arranged that operative connection therebetween is eiected merely by movement of said unit toward and upon said head at said predetermined position; and means between said clutch means and registering means for imparting motion to the later as relative rock movement between said head and rock member takes place.

20. In a torque measuring wrench having a head rockably supporting a rock member and spring means opposing relative rock movement between said head and rock member; a pressure indicating unit for measuring the extent oi' relative rock movement of the head and rock member in terms of pressure applied which comprises a support member, means for detachably securing said support member in a 'predetermined position upon the head, rotatable means carried by said support member and indicating extent of relative movement of the head and rock member, means including a pin element carried by said support member and adapted to be operably associated with the rock member merely by movement of the indicating unit toward the latter, and means between said pin element and said registering means for imparting movement of said pin element to said registering means.

` HERMAN W. ZDM/IERMAN. 

